Improvement in calipers



F. 0. WASHBURN Calipers. Y l

No. 45,894,.- v Patented Jan. 10,1865,

UNITED STATES PATENT DEEICE..

F. O. WASHBUBN, OF MILLVILLE, MASSACHUSETTS, ASSIGNOR T() HIMSELF AND JOHN C. SCOTT, 0F SAME PLACE.

IMPROVEMENT IN CALIPEPLS.

Specication forming part of Letters Patent No. 415,894, dated January 10, 1865.

To @ZZ whom, t may concern.-

Be it known that I, F. C. WASHEURN, of Millville, in the county of Worcester and State of Massachusetts, have invented a new and useful Improvement in Calipers; and I do hereby declare that the following is a full, clear, and exact description thereof, which will enable any person skilled in the art to make and use the same, reference being had to the accomjlanying drawings, making a part of this speciication, in which- Figure l is a side view of a pair of calipers constiucted according to my invention 5 Fig. 2, an edge view of the saine.

Similar letters of reference indicate the saine parts.

This invention consists in the arrangement of the index and graduated plate by which the distance between the ends of the prongs is indicated.

By means of this improvement the use of two separate tools, as is now required for the purpose, is avoided.

A A represent two bars which cross each other and are connected together by a joint, B, which may be constructed in the usual way or in any proper manner. The pintle a of this joint has an index C, attached to one end of it. The prongs b b at one side of the joint B are straight, but may be made of slightly taper torni,- and have each a small spur or projection, c, extending laterally from their outer ends, as shown clearly in Fig. l, and one of said prongs b may be graduated into inches and fractional parts thereofI to serve as a measure or rule, as is also shown in Fig. 1. The prongs b b at the other side of the joint B are curved nearly in semicircular form, like those of an ordinary pair of calipers, (see Fig. 1,) and these prongs project from the joint B the same distance as the prongs p-that is to say, in a straight line without considering the extent of the curvature ot the prougsp. Hence it will be seen that when the prongs are moved and adjusted at one end, those at the opposite end will be correspondingly moved as the joint B is equidistant between the extreme ends of the prongs I) b 1) b.

To one. of the curved prongs b there is attached by a pivot, b, a plate, D, which is slightly curved and projects across the other prong, b', and has a curved slot, c, made in it, through which a setscrew, j', passes into the other prong, b. The plate D is graduated, as shown at g, and the index C works over the graduated portion g of said plate, and indicates the extent of the spacebetween the ends of the prongs. The calipers may be set accurately by means of this index and the graduations on plate D.

From the above description 1t will be seen,

that if a piece ot' shafting is to be turned to I t in to a hole or bearin g ot' a certain diameter, the prongs b are set to correspond to the desired diameter of the hole at the same time the prongs b are set to correspond to the desired diameterlot' the shaftin g, and hence thel trouble of setting two diii'erent implements to effect this end is avoided, and a very convenient and useful implement obtained.

Having thus described myinvention, what I claim as new, and desire to secure byLetters Patent, is-

The index C and graduated plate D, when arranged an d applied to the calipers, substantiall y as and for the purpose specified.

F. O. WASHBURN.

Witnesses T. T. SMITH, O. A. FAIRBANK. 

